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Thread: GM Oil Pressure Swithch question

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    GM Oil Pressure Swithch question

    I'm working on a 04 Cavalier with a Ecotec 2.2 DOHC and it has the CSI ignition system. 116,000 miles

    I would like to know "does this year model Cavalier have the Oil Pressure Switch, that supplies voltage to the fuel pump after initial prime, once the oil pressure comes up to specs?"

    Cavalier Symptoms

    Engine just quits, while running, kinda like it looses electrical power, however it will restart after I turn the Ignition key to the off position, then back to the start, and it will run, but the symptoms continue.

    When I go through the motions of starting the engine. I turn the key from the off position to the start position. The fuel pump relay energizes, and fuel pump primes, then the engine will start and run, no problem, but after about 5 minutes or so it has the quitting issue.

    I notice this issue more at idle, than higher RPMS....this making me think maybe the Oil Pressure Switch is the type that, if going bad, will not allowing the power to the fuel pump for continuous running.

    The fuel pressure, and volume is per specs, also I have installed a new fpr. The tank is 3/4 full of fuel. I have checked all the grounds that I can see.

    I would appreciate any information on this issue. I'm not an ASE Tech, nor do I have any sophisticated engine diagnostic equipment, but I troubleshot the "Old School Way" however this issue has me stumped. I do respect those that have the credentials, and the ability to do this type of troubleshooting. It is a real head scratchier

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    The oil pressure sensor on the Ecotec only senses the pressure and if it is low. Are you showing any check engine lights? it soulds like the car is messing up when you go into closed loop, meaning it starts using the O2 sensor.
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    Forum Participator Array lovetowrenchit's Avatar
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    The oil pressure sensor on the Ecotec only senses the pressure and if it is low. Are you showing any check engine lights? it soulds like the car is messing up when you go into closed loop, meaning it starts using the O2 sensor.
    Cinpro Quoted Post
    Thanks for the input. I know some GM use the oil pressure switch circuit to power the fuel pump, once initial prime and running, wasn't sure if this engine had that set up..thanks for answer to that question...this engine shuts off in both closed and open loop, but will always restart

    No CEL at the moment

    My next move will be troubleshooting the CSI ignition, however the manual I have for it doesn't cover that procedure.
    Any info on that would be appreciated. This is a close friends daughters car, and I'm just helping out

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    Does it start and run for awhile. Then sputter and die. Wait a few min and it restarts just fine?
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    Forum Participator Array lovetowrenchit's Avatar
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    Does it start and run for awhile. Then sputter and die. Wait a few min and it restarts just fine?
    Cinpro Quoted Post
    yes, it starts up fine...it will not sputter when it dies, it just dies, no unusual noises during the dieing issue, it will restart immediately, but only after I turn the KOKO.

    I just changed the fuel filter, so I have eliminated that as possible cause

    have a manual for this car, but I know it doesn't cover all the problems that could pop up

    I'm working on this car for a close friend, daughter, who needs it for college commute
    Last edited by lovetowrenchit; 09-07-2014 at 11:20 AM.

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    Do you have a way to monitor the fuel pressure?

    The ground from the head to the cam cover is solid?

    Nothing is difficult; some things just take more time.
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    I was thinking the cat might be , clogged. But if it will start right back right after it dies that's not it.
    http://i11.photobucket.com/albums/a174/Cinpro/jokercopy2.jpg

    It's not what you buy,it's what you build!

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    Forum Participator Array lovetowrenchit's Avatar
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    Do you have a way to monitor the fuel pressure?

    The ground from the head to the cam cover is solid?
    thewizard Quoted Post
    yes, I have a fuel pressure hooked up, and it is within specs, however I'm not ruling it out, it still could act up at any time. The ground strap to head and cam cover on, and installed in correct position. I have done major work to this car a few months ago, and it was running perfect until about a few weeks ago.

    I have more info I'm going to post in a second
    thanks for your input. I appreciate it

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    Forum Participator Array lovetowrenchit's Avatar
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    for some reason I'm not getting instant emails... but will try to keep looking at this thread..I'm also on "Ericthecarguy" trying to get some insite there also on this issue, and " staying dirty" lol hope y'all don't mind? just don't want all my eggs in one basket

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    Forum Participator Array lovetowrenchit's Avatar
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    here is what i just posted on "EricTheCarGuy" forum , it may help someone else when the issue is resolved

    Okay, I changed the fuel filter today, was going to do it yesterday, but wife issues comes first Always

    Here is the outcome...same symptoms, however the old filter needed changed out. The old filter was dirty, and blackish gas poured out of it.

    I thought the GM oil pressure switch was part of the fuel circuit on this car( like it is on most GM vehicles, so I have read) and possibly causing the engine to just shut down because of it being defective(since the pump relay only operates at start up)that was not the case.

    I looked at the wiring diagram in the manual I have, and it showed only one Tan/Blk wire for the oil pressure sensor, thus blowing one of my possible causes of this issue

    I guess once the pump relay drops out, the PCM takes over supplying the voltage to the pump? my book is vague in lots of troubleshooting areas.

    Well,today I have done the Power Balance test, and all cylinders have the same drop in RPMS.

    I put the fuel pressure gauge back on the Cavalier, and get 50psi on initial KOEO, and get 48psi while engine is running at idle. When the engine dies, the fuel pressure only drops a few psi, and when I manually cut the ignition off I get 44psi for for a short while like 20 minutes or so. The fuel pressure acts more normally now, but I'm still not ruling out the fuel pump at this point.

    Now the other part that I thought was causing this issue was the fuel pump relay, however I think I have ruled that out, by taking the cover off and watching the contacts when Initial KOEO, and when the engine just quits.

    I have checked all the grounds per the electrical schematics, and all are clean, tight, and in correct places.

    I'm now trying to figure out which direction to go with my troubleshooting...I feel like it's an electrical issue, and possibly the ICM which is part of the CSI system, however my manual doesn't give basic testing on this system, or my OTC book is crap.

    I do have a cheap code reader with limited LD and will post my PIDs , and maybe someone who is better trained reading these could point me in a direction I need to go, and again thanks for all the help in resolving this issue. I don't give up easily, and may be getting close to my limit when it comes to troubleshooting this issue.

    LD Pids at Idle

    Fuel System 2 N/A
    Calc Load (%) 22.4
    ECT (*C) 84-85
    STFT B1 (%) 5.5-7.0
    LTFT B1 (%) 0.0
    Map (Kpa) 32
    Engine RPM 612-625
    Veh Speed 0
    Spark Advanced (*) 7.0-10.5
    IAT (*C) 46
    TPS (%) 10.6

    O2s Loc B1S1_ _ B2s_ _

    O2s B1 S1 (V) 0.85-0.840
    STFT B1 S1 (%) 6.3-8.6

    O2s B1 S2 (V) 0.085- 0.720
    STFT B1 s2 (%) 99.2

    thanks for any help interpreting these numbers. I do understand some things but not all

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    Forum Participator Array lovetowrenchit's Avatar
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    don't know why my avatar is a Cat? can I change that? Lol

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    Forum Participator Array lovetowrenchit's Avatar
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    I was thinking the cat might be , clogged. But if it will start right back right after it dies that's not it.
    Cinpro Quoted Post
    I was thinking the same thing, and we both agree it's not the problem
    thanks!

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